2.6.33-stable review patch. If anyone has any objections, please let us know.

------------------

From: Krzysztof Halasa <khc@pm.waw.pl>

[ Upstream commit 31f634a63de7068c6a5dcb0d7b09b24b61a5cf88 ]

tx_queue is used as a temporary queue when not allowed to queue skbdirectly to the hw device driver (which may sleep). Most paths flushit before returning, but ppp_start() currently cannot. Make sure wedon't leave skbs pointing to a non-existent device.